Combined water heater and air conditioner of the heat pump type



March 24, 1953 A. w. RUFF l 2,632,305

COMBINED WATER HEATER AND AIR CONDITIONER A /r OF THE HEAT PUMP TYPE Filed Jan. 5, 1951 '5 Sheets-Sheet l INVENTOR' ATTORNEY March 24, 1953 A w, RUFF 2,632,306

COMBINED WATER HEATER AND AIR CONDITIONER OF' THE HEAT PUMP TYPE Filed Jan. 5, 1951- 5 Sheets-Sheet 2 ATTORNEY March 24, 1953 A. w. 'RUFF 2,632,306

COMBINED WATER HEATER AND ATR CONDITIONER 0E THE HEAT PUMP TYPE Filed Jan. 5, 1951 5 Sheets-Sheet I5 1N VENTOR ATTORNEY Patented Mar. 24, 1953 COMBENED WATER HEATER AND AIR CON- DITEONER OF THE HEAT PUMP TYPE Alonzo W. Ruff, York, Pa., assignor to V. C. Patterson da Associates, Inc., York, Pa., a corporation of Pennsylvania Application January 5, 1951, Serial No. 204,658

Claims.

This invention relates to heat pumps, and more particularly to apparatus of this type ior performing the combined function of heating water and air conditioning. My two prior U. S. Patents Numbered 2,515,093 and 2,516,094 relate to heat pump water heaters of this general type, and the instant invention is concerned with certain improvements over the apparatus shown in these patents.

It is well known that a heat pump designed for heating, at maximum efciency, involves operation at temperatures and p-ressures which are not always conducive to optimum air c-onditioning and dehumidifying. The latter requires a lower evaporator temperature and a higher air range through the cooling coil. With a fixed refrigerating system, and the same air temperature, this is accomplished by reducing the air quantity over the cooling coil, which in turn reduces the heat transfer rate and the suction pressure drops with resultant lower evaporator temperature. This in turn results in a higher air range for this smaller air quantity and greater moisture condensation.

A heat pump water heater such as shown in the above-mentioned patents, will, of course, furnish air conditioning and dehumidifying, only while heating water in response to whatever type control, manual or automatic, used for controlling water temperature. In the event that manual control is used and the switch left on after the water in the storage tank is up to desired temperature, continued functioning of the heat pump would result in increasing water temperature above the desired point. This rise in water temperature results in a corresponding rise in condensing temperature of the heat pump and an accompanying rise in the compressor discharge pressure, to an inecient and even dangerous level.

Accordingly, it is an object of this invention to provide a heat pump of the general type shown in my two prior patents which will function with improved efiiciency both as a water heater and as an air conditioner and dehumidifier.

It is a further vobject of this invention t0 incorporate in such apparatus, control means which will function automatically to control the operation of the heat pump in response to demands for either air conditioning and dehumidifying or water heating.

It is a further object oi this invention to provide an improved and more eiicient heat pump apparatus for performing the above functions.

In general the objects of this invention are achieved by providing means to render the water temperature control ineffective, in order to permit air conditioning and dehumidiiying action in response to either automatic or manual demand for the same. In order to insure against excessive water temperatures and correspondingly excessive compressor discharge pressures, a valve is provided to bleed hot water from the tank, and this valve is provided with actuating means which may conveniently be governed by the compressor discharge pressure.

This valve then replaces the thermostat in controlling the temperature of the water in the tank during extended periods of air conditioning demand. Itis also desirable to lower the evaporator temperature for most effective dehumidifying action and this may be done by reducing the air now over the evaporator in any convenient manner. One convenient means for reducing air flow is to reduce the speed of the circulating fan.

The apparatus and operation of this invention may be more fully understood from consideration of the following specication, in conjunction with the attached drawings in which:

Figure 1 shows, in somewhat diagrammatic form, the general heat pump arrangement together with the basic control circuit,

Figure 2 is a side View in section of the heat pump apparatus,

Figure 3 is a top plan view and Figure 4 is a section on line 4-4 of Figure 2,

Figure 5 shows an alternative valve control arrangement.

Figure 6 shows in diagrammatic form auto-` matic control means for the heat pump.`

Figure 'I shows an alternative location for the bleed valve.

Referring now to Figure 1, l0 indicates theV rator structure, in the direction indicated by thev arrows. The compressor discharge line indicated at i5, connects the high side of the compressor4 The suction line 'i6 to the heat exchanger l2. connects the evaporator to the compressor inlet and line Il connects the heat exchanger to theA evaporator through a thermal expansion valve I8.

The heat exchanger l2 comprisesseveral parts as follows:

A hollow cylindrical member I9, disposed in a vertical plane, has an extension 2B of high side line l5 running concentrically therein, to a point adjacent the top thereof, so that hot gaseous refrigerant is discharged from the compressor at the top of the heat exchanger. From this point a plurality of lines 2| provide parallel paths of flow for the hot refrigerant in heat exchange relation to the water in the tank down to the point when these lines rejoin the cylindrical member IS. Here the refrigerant passes back into the annular space dened by the two concentric members I9 and 2t. A liquid subcooler coil 22 is located in the bottom of the tank, and is connected between the lower end of the heat exchanger l2 and the line Il.

As disclosed in two prior patents, the heat pump is initially charged with a suicient quantity of refrigerant to maintain during operating conditions a substantial liquid column in the bottom of the heat exchanger l2. Further, as disclosed in my prior patents, the water straties in temperature levels in the storage tank and the heat exchanger includes during normal operating conditions, a desuperheating stage located in the upper portion of the tank, a condensing stage located in the midsection of the tank and a subcooling stage located in they lower or bottom part of the tank. The Ymotor compressor unit is mounted in heat exchange relation with the water in the upper part of the tank.

Water inlet and outlet connections are indicated at 23 and 24, respectively, and a baffle plate 25 may be placed just above the subcooling coil to aid in maintaining the desired temperature stratication of the water in the tank.

A suitable thermostat 26, positioned preferably at about the middle or Waist portion of the tank, may be used to control the transfer of heat tothe water in the tank and if used alone, it will maintain desired water temperatures. On this basis, the heat pump, when activated by va fall in Water temperature, will function to raise the temperature of the water in the tank and at the same time cool and dehumidify the surrounding atmosphere so long as the heat demand exists through the thermostat. As soon as there is no further demand for heat, the heat pump stops. In many instances, it is desirable to have the heat pump continue to run after the water in the storage tank is up to the desired temperature, in order f to have the continued benets of cooling and dehumidifying the ambient air. In order to permit this type of operation, there is provided a. two position: switch 2l which when placed on contact B bypasses the'current fromy the. supply directly to the motor compressor unit and fan, so that the heat pump may function regardless of they thermostat 26'. Switch 2B is a two position switch and is for the purpose of controlling the speed of the fan I4.

The inclusion of the above described switches will provide for continuous heat pump operation, but some additional control is necessary to regulate Water temperature during extended periods of operation. Without such additional control means, the temperature rise in the tank would be prohibitive, and this would be accompanied by a rise in pressure on the discharge side of the compressor. The-latter pressure-rise would reduce the eiciency of the heat pump and if allowed to continue this pressure could reach dangerous proportions.

One solution would be to provide a separate condenser through Which refrigerant could be bypassed but. this involves additional bulk and eX- pense which is undersirable in apparatus of this type which is primarily designed for domestic use.

A simpler solution is to provide means for bleeding off water to waste, as by the valve shown at 29 in Figure l. This vali-e may be controlled in a number of ways, but as shown it is connected by line 3G to the discharge side oi the compressor. With this arrangement, hot water will be bled from the tank in response to a predetermined rise in compressor discharge pressure. Since the bleeding oi of hot water will automatically result` in the entry of cold water to the tank through inlet 23, the overall tank temperatures Will be stabilized and this also serves to maintain the compressor discharge pressure within safe predetermined limits.

The circuit controlled by switch 2l may be conveniently controlled by a thermostat or humidistat indicated by the reference numeral 3l as shown in Figure 6, or it may be manually controlled. While switch 28 is preferably manually controlled and pre-set when the apparatus is originally installed, it could also be placed under control of a thermostat or humidistat An alternate location for the bleed-oli valve is shown in Figure 7 at the base of the hot water outlet pipe 2:1. This valve as shown in Figure l is of the spring biased normally closed type and adapted to be opened by a predetermined rise in compressor discharge pressure. Obviously other means oi control could be used and one such equivalent is shown in Figure 5. A second Water temperature control thermostat 3.2 is mounted similarly to thermostat 26 and connected to operate a solenoid controlled bleed-oli valve 33. Since this type of valve is either closed or open, i. e. no intermediate position, a throttle valve 3.4 would have to be connected in series with the bleed-off valve to adjust the rate of ilow. As a practical matter thethermostat 32 would be set about l0 degrees higher than thermostat 26.

Referring now to Figures 2, 3, and 4 of the drawings the actual structural embodiment of the improved heat pump apparatus of this invention is shown in greater detail. Corresponding parts are given the same reference numerals throughout the drawings.

The storage tank lil is surrounded by a layer of heat insulating material 35 and the whole is enclosed by an outer cover et. The motor-compresser unit which may conveniently be of the hermetically sealed type, is mounted in any suitable fashion as for example on brackets 31 as shown. The important consideration in the mounting of this unit is that it be placed in heat exchange relation with the. water in the tank. As shown in the drawings, the upper portion of the tank. has a U-shaped pocket and the unit is mounted in this pocket so that it is surrounded at the sides and bottom by the walls of the tank. Since the insulation 35 extends completely around the tank l, the waste heat of the motor compressor unit is sealed in and transferred to the water in the tank.

The baiile plate 25, may be supported within the tank by welding it to the heat exchanger IZ as. shown.

Stop valves Sil and 39 are manually operated and provide means for isolating the thermal expansion valve it in the event that it requires servicing.

The evaporator structure I3 may ybe bolted to the topic-f the tank and held in place by the bolts 6? and plates il and @2. The ian i4 which serves to circulate air over the heat exchange surfaces of the evaporator is mounted in any suitable manner on the cover plate 42.

From the foregoing, it will be apparent to those skilled in the art that the apparatus herein disclosed` represents a preferred embodiment of an improved heat pump apparatus. All the features of maximum coefficient of performance, compactness and simplicity of installation disclosed in my prior patents referred to above have been retained. The improvements embodied in the apparatus of this invention are pointed out with particularity in the appended claims.

I claim:

l. Combined water heating and air conditioning apparatus of the heat pump type comprising in combination: a hot water storage tank; a refrigerant evaporator for absorbing lheat from, cooling and dehumidifying the surrounding atmosphere; heat transfer means of the type in which refrigerant is circulated, said means being disposed in heat exchange relation to the water in said tank, extending substantialy from top to bottom thereof and including, during normal operating conditions, a desuperheating stage located adjacent the upper part of said tank, a condensing stage located substantially at the midsection of said tank, and a subcooling stage located adjacent the bottom part of said tank in which the refrigerant is maintained in liquid phase; means connecting said subcooling stage to said evaporator, said means including an expansion device; a motor-compressor unit connected to pump refrigerant from said evaporator at low pressure and deliver said refrigerant at high pressure to the desuperheating stage of said heat transfer means; lmeans responsive to the temperature of the water in said tank to control the transfer of heat thereto; electrical switching means for rendering said temperature responsive means ineffective, in order to permit continued air conditioning irrespective of Water temperatures in said tank; and valve means for bleeding hot water from said tank during periods of extended air conditioning demand.

2. Apparatus as dened by claim 1 and including means to control the air flow over` the evaporator to improve the eiiiciency of the heat pump as an air conditioner.

3. Apparatus as defined by claim 1 in which said valve means comprises a spring-biased valve, operative in response to a predetermined rise in compressor discharge pressure.

fi. Apparatus as defined by claim l in which said valve means comprises a thermostatically controlled valve the thermostat being positioned to be responsive to water temperatures within the tank.

5. Combined water heating and air conditioning apparatus of the heat pump type comprising in combination: a hot water Storage tank; a refrigerant evaporator for absorbing heat from, and cooling and dehumidifying the surrounding atmosphere; heat transfer mea-ns of the type in which refrigerant is circulated, said means being disposed in heat exchange relation to the water in said tank, extending substantially from top to bottom thereof and including, during normal operating conditions, a desuperheating stage located adjacent the upper part of said tank, a condensing stage located substantially at the midsection of said tank. and a subcooling stage located adjacent the bottom part of said tank in which the refrigerant is maintained in liquid phase; means connecting said subcooling stage to said evap- 6. orato'r, said means including an' expansion .device; a motor-compressor unit connected to pump refrigerant from said evaporator at low pressure and deliver said refrigerant at high pressure to the desuperheating stage of said heat transfer means; a first electric switching means to control the transfer of heat to the water in said tank; whereby the water in the bottom part of the tank is maintained at a temperature below the temperature of the refrigerant in the condensing stage; a second electric switching means connected to interrupt the circuit to said iirst switching means and connect said motor directly to a source of power in order to permit continued heat' pump operation irrespective of the position of said first switch; a valve connected to bleed hot water from said tank; and means responsive to' the discharge pressure of said compressor for controlling said valve, whereby the temperature of the water in said tank is controlled by bleeding action of said valve in response to a predetermined discharge pressure of said compressor when said Second switch is actuated.

6. Apparatus as defined in .claim 5 including a rst thermostat mounted in heat exchange relation to the hot water in said tank and connected to control said first switching means, and a second thermostat mounted in heat exchange relation to the surrounding atmosphere and connected to control said second switching means.

'7. Apparatus as defined by claim 5, including a thermostat mounted in heat exchange relation to the hot water in said tank and connected to control said first switching means, and a humidistat mounted to respond to the water content of the surrounding atmosphere and connected to control said second switching means.

8. Combined water heating and air conditioning apparatus of the heat pump type comprising in combination: a hot water storage tank; a refrigerant evaporator for absorbing heat from, cooling and dehumidifying the surrounding atmosphere; means for circulating air over the heat exchange surfaces of said evaporator at a variable rate; heat transfer means of the type in which refrigerant is circulated, said means being disposed in heat exchange relation to the water in said tank, extending substantially from top to bottom thereof and including, during normal operating conditions, a desuperheatng stage located adjacent the upper part of said tank, a condensing stage located substantially at the midsection of said tank, and a subcooling stage located adjacent the bottom part of said tank in which the refrigerant is maintained in liquid phase; means connecting said subcooling stage to said evaporator, said means including an expansion device; a motor-compressor unit connected to pump refrigerant from said evaporator at low pressure and deliver said refrigerant at high pressure to the desuperheating stage of said heat transfer means; means responsive to the temperature of the water in said tank to control the transfer of heat thereto; electrical switching means for rendering said temperature responsive means in effective, in order to permit continued air conditioning irrespective of water temperatures in said tank and for reducing the rate of iiow of air over the heat exchange surfaces of said evaporator; and means responsive to the discharge pressure of said compressor for bleeding hot water from said tank for stabilizing water temperatures and holding the condensing pressure within predetermined limits.

9. Apparatus as defined by claim 8 which incln'des a. variablev speed electric.. fan for' forced circulation of air overl the heat exchange surfaces:

of said evaporator.

l0. A combined Water heater and air conditioner of the heat pump type, in which a refrigerant is used as the working fluid, comprising in combination: a hot water storage tank having a recessed pocket at one sidey of and adjacent the top thereof; a refrigerant evaporator mounted on said tank and adapted to absorb heat from the ambient air at the prevailing temperature; a heat exchanger of the type in which refrigerant is circulated, disposed within said tank at one sidethereof and extending substantially from top to bottom thereof; a motor-compressor unit mounted Within said depression in heat exchange relation to the water in the upper part of said tank; closed uid conduits extending between said compressor and the'evaporator and heat exchanger to enable the compressor to withdraw gaseous refrigerant at low pressure from said evaporator and deliver said refrigerant at high pressure to the top of said heat exchanger; means including a closed conduit for refrigerant and an expansion device connecting the bottom of, said heat exchanger and said, evaporator; means re-i sponsive to the temperature of the water in the tank to control the transfer of heat thereto; and additional means to control the air flow over the evaporator to improve the efficiency of the heat pump as an air conditioner.

ALONZO W. RUFF.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS 

